The increasing costs and negative environmental impact of fossil-fuel based energy production are driving the search for sustainable alternative energy sources. Solar radiation is one source that has the potential to meet the projected energy demand in the 21st century. See H. B. Gray, Nature Chemistry 1, 7 (2009); N. S. Lewis and D. G. Nocera, Proc. Natl. Acad. Sci. USA 103, 15729 (2006). Photovoltaic (PV) solar energy conversion devices dominate the market, with 13.9 GW of generating capacity installed worldwide through 2008 (1.1 GW in the United States). See S. Price and R. Margolis, 2008 Solar Technologies Market Report, Department of Energy (2010), pp. 119.
The mismatch between power production capability and demand is a critical limitation of PV devices: the loss of power generation at night is the most obvious example. One alternative involves the conversion of radiative solar energy into a chemical fuel that can be produced when sunlight is available and consumed when it is needed. Solar water splitting to produce hydrogen and oxygen has long been a primary research objective in this area. The chemistry of water splitting requires catalysts that can couple the individual electrons and holes generated by light absorption to the multielectron redox reactions involved in the production of hydrogen and oxygen. In the ideal case, a single material will perform both light absorption and multielectron redox catalysis. Combinatorial methods are well-suited to the challenge of discovering new materials with the potential to effect photoelectrochemical (PE) water splitting. See M. Woodhouse and B. A. Parkinson, Chemistry of Materials 20, 2495 (2008); M. Woodhouse and B. A. Parkinson, Chem. Soc. Rev. 38, 197 (2009).
There is a need for systems and methods for efficient and rapid screening of candidate photoactive materials as electrode materials for solar fuels production.